This invention relates to the sealing of shafts in general and more particularly to an improved shaft sealing ring.
A shaft sealing ring including a stiffening ring having an angular profile and a lip ring with a sealing lip connected thereto by an intermediate ring in the nature of a diaphragm and in which an elastic contact pressure element is provided for pressing the sealing lip resiliently against the surface of the sealed shaft is described in German Pat. No. 10 07 130. In the disclosed sealing ring, the lip ring has a groove at its outer circumference, in which a coil spring is embedded in the immediate vicinity of the sealing lip. The fabrication and assembly of this coil spring, however, results in an undesirable increase in the cost of the shaft sealing ring and it is often difficult to produce uniform contact pressure over the entire circumference. This is true particularly for small nominal diameters, where the hardening caused by the joining of the two ends of the coil spring extends over a zone which occupies a substantial percentage of the total circumference.
U.S. Pat. No. 2,267,930 teaches a shaft sealing ring in which the contact pressure element extends into the interior of the lip ring. More specifically the contact pressure element extends into the immediate vicinity of the sealing lip. However, the operating properties of this sealing ring have also not been found to be completely satisfactory. With this sealing ring good sealing results can be obtained, for instance, only if steps are taken to ensure that the sealed shaft is running absolutely true, and only if the specified outside diameter of the sealed shaft is maintained with the greatest precision. Both requirements cannot be met when ordinary manufacturing tolerances are maintained.
It is thus an object of the present invention to develop a shaft sealing ring which, with ordinary assembly tolerances, ensures good sealing, which is inexpensive to manufacture and which in quantity production exhibits the greatest possible repeatability in the quality features of each unit.